Seagate Momentus xt or intel ssd????

No question in my mind, the SSD is superior.

The momentus speeds up reads, but with only 32gb, not all of your data will be in the cache, available for a fast read.
And, when it comes time to write, you are still limited by the mechanical speed of the hard drive.

It seserves a place in a laptop where you are limited to one drive, and a ssd won't hold it all.

In a desktop, start with a ssd, and later add a hard drive for bulk storage if you need to.